The literature review and survey of 132 pharmacists revealed that while 47 percent reported that they had encountered a patient with a suspected adverse event, only 1.5 percent reported this to Health Canada. In contrast, 19 percent of the pharmacists had reported adverse reactions to prescription or non-prescription drugs.

“The data show that adverse events are not being reported or are being under-reported at a dramatic rate,” said Dr. Sunita Vohra, one of the study authors and an associate professor of paediatrics at the University of Alberta, Canada. “Natural health products should be treated with due respect.”

While the number of potential adverse events is low relative to the rates of NHP use in Canada, such products may be effective, but they may also have side effects, Vohra said. NHPs include such products as vitamins, minerals probiotics, St. John’s wort, echinacea and garlic.

In the survey, the majority of pharmacists felt they knew enough about just two drug-health product interactions to counsel patients. Adverse reactions can range from mild rashes and headaches to much more serious effects by patients using prescription medication such as blood thinners or insulin.

And while the pharmacists reported that they spent up to 30 minutes per day counselling patients on the use of natural health products, they estimated that only five per cent of patients who purchase products ask about potential drug interactions. “The public is less likely to see natural health products as risky,” Vohra noted.

The lack of available data on interactions makes it difficult to provide patients and health care workers with useful advice for managing adverse reactions associated with these products. “To improve patient safety, new ways of capturing data are necessary,” Vohra said.